Excel: 'not enough memory continue without undo'

This is a message a friend of mine gets and I'm posting it for her (really, it's not a problem I'm having ).
This occurs when she has 2 excel files open (nothing else running) and is copying about 70 rows of data from one file and pasting in the other file (very small amount of data). It starts by taking a few moments to do the pasting, then sloooowly pastes some of the data and then before it finishes the program hangs up for 5+ minutes and she has to force quit. All updates are installed and this is excel 2008. She has a MB 13", 2.13GHz, 2GB RAM, OS 10.6.x, 160GB HDD. (HDD is not even close to full)

Any suggestions?? Thanks as always for the help.